Kinetic Studies of Methylene Blue Adsorption on to Activated Carbon Prepared from Plantain Pod (Musa paradisiac)

Abstract

The mechanism of adsorption for methylene blue from aqueous solution using an activated carbon prepared from plantain pod was studied at varying time. The adsorption reached at equilibrium in 90 minutes of contact time. The kinetic data were fitted to the pseudo first-order, pseudo second-order, and intra- particle diffusion models. The pseudo first and second order rate constants were found to be 0.0152 min-1 and 4.22×10-5 g/mg.min with correlation coefficient of 0.930 and 0.931 using dye concentration of 75 mg/l. Isotherm studies were also conducted by increasing the mass of adsorbent. The experimental data obtained at temperature of 30ºC were fitted in to Langmuir, Freundlich, Tempkin and Dubinin-Raduskevich adsorption isotherm models respectively. The correlation coefficient (r2) of Langmuir, Freundlich, Tempkin and Dubinin-Raduskevich adsorption isotherm models were found to be 0.993, 0.991, 0.999, and 0.986 respectively. Based on Dubinin-Raduskevich adsorption isotherm model, mean free energy was determined to be 0.03535 J/mol, < 8 the adsorption process can be described as physisorption.